Process of making firm, almost entirely waterproof, non-slipping leather.



i To all whom it may concern:

,- Tan s' rnrns ra'rnn'r oFFicn.

rnrrz KORNACHER, or nnnnnnon, GERMANY.

PROCESS OF MAKING FIRM. ALMOST ENTIRELY WATERPROOF, NON-SLIPPING LEATHER.

1,91 ,113,267 Specification of Letters'Patent.

No Drawing.

Be .it known that I, Fnrrz ICORNACIiE-R, manufacturer, citizenof the Empireof Germany, residing atQ-Xuerbach, Germany, have invented certain new and useful Improvements in Processes of Making Firm, Almost Entirely Waterproof, Non-Slipping'Leather, of which the following is a specification.

' It is [well known that leather exhibits greater firmness and toughness the lessthe .fibersofthe hide are changed or acted. on

during tanning. It .is also known that the firmness of leather may be considerably in-' creased and. it may be made very-waterproofbeing impregnatedvwith substances 'suchas stearin and paraflin.

V'arious processes for making firm' and waterproof leather, adapted to be employed for special purposes are based on these two circumstances, by merely vtanning the hide, preparedfor-the tanning process, by a. process (chromo tanning, alum tanning and the like) nin'g with vegetable substances, and after the leather obtained in this manner has been a dried, impregnating it with fatty, substances or a mixture of such, entirehydrocarbons and the like, 'under the application of heat.

ugly, dark, greasy'and ,smeary appearance,

and of being only able'to be worked with difficulty, and being slippery in use and con-- sequently inapplicable for many purposes. Experiments to avoid these disadvantages by subsequently removing the grease from the surfaces of the leather, always only yield defective results as, owing to the difficulty of this work, either too little grease is (lissolved or the solution istoostrong, so that the grease is forced fii lly to the surface and the appearance and quality of the leather is still further affected by having a dark color and soft spougy feel. Under these circumstances it therefore appears quite impossible;

to improve leather by a subsequent r'e-tanning with vegetable tanning sul'istances and tl'icrefore it has hitherto not been attempted in practice in this case of impregnated leather.

Now this invention relates to a process by. means of which all the disadvantages herein before 'incntioned are removed and which'has but little action on the hide fibers, and if necessaryagain tanan impregnated, firm or solid leather of unobjectionable appearance is obtained.

This prccess'mainly consists in treating pregnatecl with saponifiable" and unsaponi- 'fiable s'ol1d substances such as stearin and" paraflin, first for 13 hours in a solution 01 an alkaline bath preferably of caustic soda or the like at a strength of '5.-,10 13., the 'sap'omfiable substances found on the surface are saponified and changed, so that they may be removed b a simple washing. The con- Patented Aug. 20, 1912. Application tiled February 20, 1912. Serial No. 678,807. I

sequence of tisi is that the leather entirely loses on, the-outside itsgreasy character wlthout loslng the artificial fullness and vfirmness imparted to it by the impregnation,

and-may then be. suitably bleached and re tanned on the surfaces. The extraordinary waterproofness of the leather prevents any damage from the alkali.

The treatment for 13 hours of the hides with a sulfuric acid solution of 510 B. in strength which then follows, causes the free alkaline salts still contained in or upon the leather and the metal salts derived from "the tanning, to be neutralized and rendered non-deleterio'ils and the leather is also thereby thoroughly brightened. I

By the double vgjetable tanning, that is to say by the double treatment of the raw hides which have been preliminarily tanned with minerals, in vegetable tan liquors and after the impregnation, the leather cuts cleaner and firmer and obtains a rougher surface on the one hand and thus is'substantially better adapted for use in shoe or belt factories and on the other hand it greatly assists in. producing the appearance desired for these kinds of leather, and finally by the double vegetable tanning namely the preliminary and subsequent tannin'g, the slipping of the leather when wet isentu-cly avoided. -The final application of the said,

solutions of metal salts which then takes place, causes the conversion of any soap residues which still remain, into insoluble metal soap, so that the feel of the leather is drier and its firmness and Waterproofness is further increased.

The process iscarried out approximately as follows: The hides which have been treated as usual are subjected in a raw or chemically tanned Condition to a weak vegetable final tanning. Afterbleaching and drying, the leather is impregnated by saturating it under the action of heat with saponifiable and unsaponifiable substances together, for instance stearin and paraffin,

like.

until it is fully saturated. The leather thus treated is then exposed to the action of alkaline baths, preferably of caustic soda, of a strength of'from 5-10 B. in strength, whereupon it is treated with sulfuric acid of 51() B. in strength, then again washed, then retanned and finally treated for a short time in a solution of metallic salts, such for instance as alum, aluminum sulfate and the The dressing is done in the ordinary way by drying, pressing, rolling, finishing, etc;

The leather made in this way is extremely firm or solid, and almost perfectly waterproof but dry and clear and from its outside absolutely cannot be differentiated from unimpregnated leather. It may be dyed, finished and treated exactly like the latter and sized, ribbed and polished, it does not slip when in use, and finally exhibits all the properties which can be called for from a perfectly heavy leather such as sole leather,- driving belt leather and saddlery leather.

I declare that what I claim is:

A process-for making firm, almost perfectly non-slipping leather from vegetably tanned, or miner-ally tanned and vegetably retanned, bleached and dried hides saturated withsaponifiable and 'unsaponifiable fatty substances, such process consisting in treat ingthe leather in an alkaline bath.,- then washing it, then treating it with 'sulfuric acid, washing it again, retanning and finally treating it with a'solution-of metallic salts. v In testimony whereof I aflix my'signature in presence of two witnesses.

. FRITZ CORNACHER. Witnesses:

JEAN GRUND, CARL GRUND. 

